<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script>
			function css(){
				document.getElementById("")
				
			}
			window.onload=function(){
				var div1=document.getElementById('div1');
				alert(css(div1,'width'));
				css(div1,'background','green');
			}
		</script>
		<div id="div1" style="width: 200px;background: red;height: 200px;"></div>
	</body>
</html>
